"the curator of drawings at the National Gallery"

a public display of works of art or items of interest, held in an art gallery or museum or at a trade fair.

"an exhibition of French sculpture"

"there were accusations of plagiarism"

Barrel distortion describes a type of distortion wherein lines that are straight in real life appear to curve inwards (like the walls of a barrel). A good way to check for barrel distortion is to look for parallel lines in the area you are shooting and see if the lines appear parallel in your image.S

As a result, depth of field (DoF) is the distance between the nearest and furthest elements in a scene that appear to be "acceptably sharp" in an image. The distance between the camera and the first element that is considered to be acceptably sharp is called DoF near limit.

Partial metering covers only the centre 6.2% of the frame in the viewfinder, thus providing precise metering only for the subject. When the background is brighter than the subject due to reasons like back lighting, this metering mode is particularly useful. It is useful for back-lit shots or tiny subjects.

By definition 18% gray is the “mid-point between black and white on a logarithmic or exponential curve.” Think of it this way; it is simply halfway between black and white.

A shadow is the result of the relationship between the subject's location and the direction of the light source. With front light, the shadow falls behind the subject. When side lit, it appears on the opposite side that's lit.

Highlights are the lightest elements in an image, whereas shadows are the darkest areas. Dynamic range is the ratio between those vivid highlights and dark shadows, from bright white to pure black. That range is key to an image's depth and drama. If a photo has poor dynamic range, the image can appear flat or gray.

The PNG file format is widely used on websites to display high-quality digital images. Created to exceed the performance of GIF files, PNGs offer not just lossless compression, but also a much broader and brighter color palette.

"a JPEG image"

In film and photography, a prime lens is a fixed focal length photographic lens (as opposed to a zoom lens), typically with a maximum aperture from f2. 8 to f1. 2. The term can also mean the primary lens in a combination lens system.

DSLR is the abbreviation for Digital Single Lens Reflex. Digital means that the camera operates with a fixed, digital sensor. Single-lens means the camera uses the same lens for framing, focusing, and taking the photograph.

Crop factor or magnification factor refers to the diagonal measurement of a camera's sensor size when compared to the diagonal measurement of a traditional 35mm frame of film. The effects of crop factor are most noticeable when looking at a lens' equivalent focal length.

In Photoshop, go to Filter > Blur Gallery and select Iris Blur.